I have an older Lennox furnace. Model G1203-110-3 110,000 BTU
I replaced the thermo-couple recently. Now the burner is coming on but the fan is not always kicking on. Is there a relay to start the fan that could be bad? There is a silver box by gas valve that has electric wires to gas valve and then to fan and thermostat. Could that be problem source?
I sometimes hear a buzzing noise around furnace.
I am going to replace thermostat today. I am going to get digital type. It now has a round Honeywell type with a mercury switch in it.
Any tips fo trouble shooting? Greatly appreciated.